Overview

What we have done

We have replaced and improved the gates and operating equipment at Hardmead Sluice. The previous gate had reached the end of its working life after 45 years of service. A failure of Hardmead Sluice would have increased flood risk and loss of control of upstream water levels for navigation, water supply, amenity and environmental needs.

The previous single sluice gate has been replaced with two smaller gates to give greater flexibility in operating and maintaining them and to create space to install fish and eel passes through the structure as the previous sluice acted as a barrier to the free passage of fish and eels.

The main works started in August 2022 and were taken over from the contractor in mid-July 2024, having been substantially operational since the beginning of the year.

The new sluice

The finished replacement works include two new tilting weir gates, a new bridge with the gate drive mechanisms on it, a new maintenance access bridge at the upstream end, a fish pass, a pumped eel pass, new stoplogs (to isolate a gate for maintenance), supporting control equipment, remote monitoring of the gate operation and new access surfaces around the site to current standards.

Above: An overview of the finished works

The new bridge supporting the drive mechanisms for the two new sluice gates

Above: New tilting weir gates with flow dividers to ensure air can get behind them, smoothing their movement. Pipework assists emptying a gate chamber for maintenance.

With the previous gate at Hardmead Sluice, water flowed underneath it generating strong underwater currents. The new tilting weir gates have water flowing over them reducing the underwater currents and allowing small debris to be washed over. All sluices are hazardous and the water around them should not be entered. All the sluice equipment is behind locked gates with suitable warning signage in place.

How will the sluice operation affect me?

With the major construction works at Hardmead Sluice complete the site compound has been removed and the track past the sluice reinstated and reopened. The level of future access to the site will be for operational and maintenance checks at a similar level to the previous sluice.

We thank our neighbours and the public for their patience and tolerance during these essential works.

Above: Location of Hardmead Sluice

We will need to continue to have construction traffic use the track from Holycross Road as the similar works to replace Stanstead Sluice have started and are expected to be complete in spring 2026.

Background

The waterways in the Lower Lee valley include the River Lee Navigation, Old River Lea, and the Lee Flood Relief Channel (LFRC). The LFRC was built between 1949 and 1977 and is designed to carry flood water to reduce the likelihood of flooding in the Lower Lee valley. A system of weirs, gates and sluices control water levels in the LFRC. These maintain water levels for water supply, navigation, amenity and environmental purposes while allowing flood flows to pass during storm events.

Hardmead Sluice is a major flood control structure within the LFRC and is located at Great Amwell, close to the town of Ware in Hertfordshire. As well as managing flood risk, the sluice assists in sustaining water levels in the River Lee Navigation that also enables flows down the River Lee Amwell Magna Loop from the Tumbling Bay weir.

Our partners

We have delivered these works in partnership with AECOM, BAM, Hunton Engineering, Max Wright Limited, Jacobs, Arcadis and Stantec.

Are you prepared for flooding?

While these works will improve flood defence along the LFRC, it is important to be prepared should the worst happen. Here are some steps you can take to prepare yourself for flooding events:

Sign up to our flood warnings: www.gov.uk/sign-up-for-flood-warnings

If you are visiting the area, sign up to flood warnings or the Met office weather alerts and receive advance warning of potential flood risk: UK weather warnings - Met Office

Prepare a personal flood plan and be assured of what to do if it floods: Personal flood plan - GOV.UK (www.gov.uk)